The focus of this proposal is to continue development of a unique panel of colon cancer associated nuclear matrix proteins (NMPs), discovered and developed during our previous EDRN-sponsored, Biomarker Development Laboratory funding. NMPs offer the potential serum-based biomarkers for the early detection of colorectal cancer. This work has progressed substantially from testing of un-blinded single institution convenience samples all the way to testing of blinded, EDRN sponsored multi-institution reference sets. Markers were tested in different laboratory settings, cancer subtypes, and patient population characteristics. These data provide compelling potential for application in clinical populations. Currently two markers, CCSA-2 and CCSA-4 are poised for Phase ll-lll validation studies. We propose, with the help of established experts in assay development, to further refine those assays to position them for definitive clinical testing. In addition, we will advance NMP markers related to liver metastasis. The two major objectives 1. To OPTIMIZE AND REFINE the CCSA-2 and CCSA-4 assays and test them in a series of small scale experiments to position them for definitive evaluation within the EDRN mechanism. In specific, we aim to (a) develop robust assays for the accurate and precise measurement of CCSA-2 and CCSA-4;(b) test the assays under a variety of clinical circumstances and conditions to understand, and anticipate sources of error and potential problems in implementation that might be encountered when testing the assays on a larger scale. The goal of this first objective is to deliver two assays to validation with ample preliminary testing to maximize the potential for success in the EDRN program. 2. To develop NMP markers for liver metastasis. We have identified proteins in liver metastasis tissue specimens that are neither present in adjacent uninvolved liver nor in liver from normal donors. These proteins are prime candidates for assay development for markers of advanced disease. We propose (a) to isolate, characterize and develop antibodies for serum detection of liver metastasis proteins, (b) to evaluate these antibodies in appropriate clinical specimens for eventual delivery for EDRN validation.